Here is how it works (in the example to follow you would only get two number sets to play but ather numbers will give you more):

4

1

7

Root

sets

5

2

8

4

1

-

5

7

4

1

4

7

-

2

1

7

-

8

1

0

5

5

2

8

5

2

-

7

5

8

-

4

2

8

-

1

1

3

8

Maybe I will add a component that would utilize the 105 and 138 from above. In an instance where the result of addind the pairs gives a two digit sum I would have to write an if null statement for position one.